Abrasion shoe for airfoils



sept. 3, 1935. H, Ef WANE'R 2,013,323

ABRASION SHOE FOR AIRFOILS' Filed Feb.V 20, 1934 Patentedsepf. 3, 1935 2,013,323 I ABRASION SHOEZFOR AIRFOILS Harry E. Waner, Akron, Ohio, assigner to The B. F. Goodrich Company, New York, N. Y., a. corporation of New York Application February zo, 1934, serial No. 712,161

3 Claims. (Cl. 244-31) This invention relates to means for preventing wear of the leading edge ofv an airfoil such as a wing or a control or other member of an aeroplane by sand, hail or like material in the air stream, and its general object is to provide an effective and economical device for this purpose.

A more specific object is to provide a more effective resistance to wear than is provided by a 'mere coating of rubber in unstrained condition and further objects are to provide the stated advantages Without undesirable modification of the aerodynamic characteristics of the member and provide for .facility of mounting the device.

Of the accompanying drawing:

Fig. 1 is a perspective view ofan aeroplane and, mounted upon the horizontal lstabilizer thereof, a device embodyi m-y invention in its f preferred form.

Fig. 2 is a section on line A2 2 of Fig'. 1. 'Fig 3 is a cross-section of a rubber shoe embodying my invention in its preferred form as it appears before its applicatiomto the airfoil.

Fig. 4 is a cross-section of a similar shoe of rubber-and-fabric construction, having .advantages in the matter of attachment but somewhat more expensive.

Referring to the drawing, the device comprises a shoe of U-shape in cross-section, molded Vwith sharper curvature than that of the surface to which it is to be applied. The shoe has its of the U and its legs or wings are of diminishing thickness toward their margins, each of which preferably terminates substantially in a feather edge, fer minimum interference with the streamline form of the airfoil upon which the shoe is mounted, in conjunction with adequate thickness for long resistance to wear at the leading edge of the airfoil, Where'the impact of particles in the air stream is greatest and the abrasion most destructive in the case of an unprotected airfoil.

The shoe may be an al1-rubber member I0, Figs. 1, 2 and 3, for economy of manufacture, in which case it is applied directly to the airfoil it more highly resistant to abrasion than the lo same rubber composition is when it is in an un strained condition and much more highly'resistant than the same composition iswhen its exposed surface is under tension, as it is when a.

flat or only slightly curved sheet of rubber is l5 bent about an object of sharper curvature.

The "shoe of Fig. 4 differs from that of Figs. 1, 2 and 3 in that it comprises an outer, abrasionresisting layerl2 of rubber and an inner layer 2 or liner I3 of` fabric, the twobeing molded and vulcanized together in the sharply curved shape, the fabric layer .resisting stretching of the inner surface of the structure in the bending of the shoe to less sharply curved form in applying it 2 to the airfoil and thus putting the exposed outer rubber surface under vrelatively high compression. The fabric also may serve as an anchorage for the heads of tacks in case it is desired to tack the shoe to the airfoil and force the heads of 3 `the tacks through the rubber to the fabric. greatest Wall thickness in the vicinity of the bend I claim:

1. A protective shoe for the leading edge of an airfoil comprising a layer of rubber having in cross section, when in unstrained condition, 3 a U-shape of sharper curvature than that of the surface to which it is to beapplied.

2. A protective shoe as dened in claim 1 in which the wings of the sh are of diminishing thickness toward 'their margins.

3. A protective shoe as deilned in claim 1 comprising a lining layer of relatively inextensible material adhered to the inner surface of the rubber layer. y

HARRY E. WANER. 

